I have a new Brison 3.2 (1.5 gallons) and can't get it to run right. It has already dead-sticked on me twice.

I know that the HS needle should be between 5/8 to 1 & LS needle 1.5 to 2.5.

Here is what my settings are: HS: 1, LS: 1.5

With the LS at 2, my engine would cut if running at idle and suddenly throttled up. Now the engine burbles at mid throttle.

I am running 89 octane gas with Stihl oil at about 1:37 mix.

Also, the idle is high and the engine won't cut even when the throttle is closed all the way (Yes, I have tried it manually also)

TIA.

Cheers & Happy landings

Check Brisons instruction pages here, will you get the needles set for a starting point,
http://www.brisonaircraft.com/faqs.htm

Check your timing ring, have you been messing with it ?

Nope.
Engine was sent to Brison and they changed the sensor and ran it.

37:1 mix? I am reading my manual and it says to go 64:1 for petroleum based and 80/100:1 for synthetic. That seems like way more oil than is necessary and they even say that it could damage the engine voiding the warranty. FWIW I am running Klotz in my new Brison 3.2 at 80:1. It runs great. I know this doesn't have anything to do with your question, but I do know that my Ryobi weed wacker runs terrible if I get too much oil in the fuel. I haven't run my Brison with too much oil so I don't know if it would have the same effect. That might be something to look at.

You maybe right...
But it also says in the manual to always use the recommended ratio and that was written as 32:1.

Even Lawnboy ashless says 32:1

So do you still go with Brison's recommendation or the recommendation on the oil bottle ?

BTW: Wouldn't I see a lot of white smoke if there is too much oil in the fuel ?

Use engine manufactures recommended ratio, not oil manufacturer. You wont see much smoke with too much, but it will gum up the motor. I burn Amsoil at 100:1 in my 3.2.

I would definately go with Brison's recommendation for the simple fact that they are the ones who have to back up the warranty. I figure if I follow their recommended ratio and the engine is damaged, Brison is on the hook for the repair. If I go outside their recommendation and the engine gets gummed up, then I have to fight with an oil manufacturer to get my engine fixed. I just dug out my manual and mine doesn't say anything about using the ratio written on the bottle of oil. The bottle of Klotz I have says to use 40:1. I went with Brison's recommendation and use 80:1 since they specifically say to use a good synthetic such as Amsoil or Klotz at that ratio.

With my other gas engines (weed wacker and chain saw) I don't see any difference in the smoke with too much oil, but I definately see a difference in how they run![:'(]

I am having problems with mine and the only thing different is that I am using gas with more oil than recommended. 50:1 instead of 80:1. I plan to go back to using 80:1 and see if it gets better. My problem is that I cannot try it until June.

Allrighty then.
I will go per Brison's recommendation and see how the engine runs...

Thanks for all the answers.

Post back after the changes so we know how much effect there was.
Thanks

I will do just that. I think it was too much oil. That is the only thing I can think of.

How about my other question...

Why can't I kill the motor by closing the throttle all the way ?

I have tried this mechanically also. I have adjusted the screw for the low speed too and even taken it out all the way.

TIA.

Remove the throttle stop bolt on the carb body. even screwed all the way out it will not allow the butterfly to close completely. Then it'll stop.

What plug and gap are you guys running in your Sachs?
Thanks,

The throttle not closing all the way with the idle stop screw removed sounds like a servo travel adjustment problem. Check to make certain that the servo is moving the linkage enough to close the throttle. Having the low speed needle set too rich will also make it hard to kill.

Too much oil will DEFINITELY make the Brison run ragged. Check your plug color. If it's black or oily colored, you have too much oil. Light brown is just right. Shades of white or grey is too litle oil. I've been running one of mine on 65-1 high quality 2 stroke racing oil for about a year now, roughly 8 gallons through it, and the piston and cylinder still look new.

My low speed needle setting is just under 1 turn open. The high speed needle is about 1-1/4 open.

One thing to note, CH Electronics suggests that the air gap at the sensor be set at .020, Brison has designed their timing ring to accept the sensor with an air gap at close to 1/8" (or 100 thousandths) on the new engines. I don't understand why Brison does this. It DOES have a very detrimental effect on the performance. It will also make it appear that you are having trouble with the ignition module. The only fix is to replace the ring with one from CH. A big pain in the butt.

A follow up to my last post.

I really think that your low end needle is WAY to rich. That will keep the engine running forever at low throttle settings. Burbling on throttle up is a good sign of richness. A high oil content will foul the plug quickly and make for a rough running engine. Stay at mixtures at 60 to 1 and aove and see how that works.

Run the engine at a mid range throttle setting and tweak the low end needle for max rpm, then richen it up about 100 rpm. Then set the high end needle with a tach for max, and richen it up a couple of hundred rpm. Tweaks after all this should not be more than 1/8 turn on either needle for elevation and weather changes.

Use a well balanced and light wood prop (22/8 or 22/10) to get instant throttle response when you are setting up the engine. After it's set up, use whatever prop you want but leave the needles alone.

Talking to CH, the ignition air gap should not be a problem. I have to say that my other 3.2 that I have been running for over a year now has the same air gap and runs very well, indeed.

Brison makes a very good engine. I'm certain that the problem is a minor one.

Hi,
Check this thread for more Brison 3.2 info.
http://www.rcuniverse.com/forum/Bris...1786514/tm.htm
Good Luck

I know this will open another can of worms here...but

Brison says that it's OK to run synthetic oil from day one whereas many people who have been running gas engines suggest to run petroleum based oil for a couple of gallons before switching to all synthetic.

In fact, I think BME recommends the latter too. Now I am not saying that people on my flying fileld know more than the guys at Brison, but this actually gets to be a bit confusing.

Yes it does get confusing , i just cant make up my mind either on what to run for oil petro or sythetic from the get go. I just got a new Fox 3.2 and Fox says to run petro base oil for first 5 gallons then swith to Klotz or Amsoil. I have been using Amsoil racing seiies 2000 sythetic for the last 3 years on all my Brisons and have had good results . Good luck i think its a toss up.

The engine manufacturer knows his product better than anyone else out there. It's always better to break in the engine his way. It keeps your warranty intact.

It wouldn't hurt to run the first gallon or so with an ashless natural lube. IF you can find an ashless oil. Because of exactly that, I've been breaking in my engines on all synthetic Motil 800 two stroke motorcycle racing oil at 40/1. The Motil 800 is a VERY high quality synthetic two stroke oil, and runs clean and cool.

Brison engines ARE supposed to be run from day one on a quality synthetic oil. The older Brisons were broken in on a natural oil then switched to synthetic if desired after the first gallon.

After the break in, I reduce the oil mix down to 65/1. After a couple of years of running the engines, the pistons and cylinders still look new. The engines have never fouled a plug unless I had the mixture set too rich. The bearings are still very smooth in the races, and compressions are generally better than the day I got the engines.

The engine manufacturer is going to look for excessive wear in the pistons and cylinders if you return one. Since most of our engines should last over 500 to 1000 running hours, the best oil you can get really matters.

By the way, non synthetic oils are much more prone to causing rings to stick. At any engine age.

Next weekend I plan to get my plane in the air again and I will see if the engine runs better with a fresh mix of gas/oil.

Reference ashless oil Lawnboy is suppose to be ashless. I use it for first 3 or so gallons at 40/1 mix then switch to AMsoil racing seriies at 64/1

So ..... What's the difference between the old, and the new Brison's ? Is the metallurgy any different ? And then, what would be the difference between the metals used in a Brison, and the metals used in a Zenoah ? Or then .... Why shouldn't we break in Zenoah's from the very beginning using synthetic ?

> Jim

Direct from Harvey at Brison, he states the new lite weight pistons and cylinders and the fact the pistons only have one ring make it so. He says he has taken hundreths of motors apart and seen the affects of to much oil and poor quality oil. He recommends as stated previous use sythetics from the get go.And yes the metals are different today than they were 15 0r 20 years ago. Much stonger and durable.